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Using spin to send data on a 38kHz carrier - Page 2 — Parallax Forums

Using spin to send data on a 38kHz carrier

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  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-06-09 04:50
    @Mike Green

    I'm going to set this for 3 pulses/second and just let it run to see how long the 14,000mcd LED
    lives wink.gif Now I'm curious.

    I set it at 25 pulse/sec and after a minute you could feel some warmth from the LED when you
    put your finger on it....none really at 3/sec.

    Cranked the V up to where its passing 4amps through it...now it's REALLY bright smile.gif
    You could see this from a mile away easy.

    Be funny to use an ATtiny and a 9v battery to send a mega bright pulse once every few seconds and tie it to
    a helium balloon! instant UFO wink.gif
  • morris4019morris4019 Posts: 145
    edited 2009-06-09 16:57
    I don't really think i'll have to worry much about pushing too much power to the IR Leds. I'm running one LED at the moment off 3.3 v (anode) and cathode to 1k ohm to PROP. There will be 4, one for each direction.

    3.3v / 1k ohm = .0033 (3.3 mA)

    At first I was using a 100ohm resistor to get good range. This was before I realized how much range i would get. I don't really need a beacon that will be seen for 40' at the moment. I tested in indoors in bright light and i ran out of room at 40'. At that distance i still had about a 90 degree window that my detector would pick up the beacon, with no data loss.

    I'm looking more, at the moment, of small range beacon, that i can use to test my robot. Also, i'd like to build another beacon that i can test relaying of messages, when not in line of sight. This is going to be alot easier if i don't have to space the beacons so far apart, at the moment. But, in the future when testing is complete, I will be trying to push as much distance and power as possible.

    Thanks
    -Mike

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    ······ I'll try everything once [noparse]:)[/noparse]
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